Almond Hull-Split Prediction Model

Theodore DeJong, Department of Plant Sciences, University of California, Davis

A timely harvest is essential for maintaining almond nut quality. The ability to predict the date of almond harvest maturity as early in the season as possible would be beneficial for almond growers, because of the complicated logistics of late season orchard management and the large land area under almond cultivation. This knowledge would also aid in marketing considerations.

The model presented here was developed using data from an 8-year study conducted in three major growing regions of the Central Valley of California (south, central and north) and involved many important California almond cultivars. The model predicts a date for almond hullsplit in a location, based on user input of a date of 1% of full bloom and temperature readings during the first 90 days after bloom collected by a specific CIMIS weather station, also designated by the user.This model will only work 90 days after bloom.

This hull-split prediction model is based on the concept that the rate of fruit development from bloom to 1% hull-split is highly dependent upon early spring temperatures (Tombesi, et al., 2010). The rate of fruit development between 1% and 100% hull-split can also vary greatly among years and cultivars (Connell, et al., 2010.). To estimate the approximate time that a cultivar will be ready for harvest, you can use this hull-split prediction model coupled with the information in Table 3 of Connell, et al., 2010 to estimate 100% hull-split.